Currently, vertical cavity surface emitting lasers (VCSELs) are implemented as one type of semiconductor laser.
In the basic structure of a vertical cavity surface emitting laser, a first multilayer distributed Bragg reflector (DBR) layer is formed on an insulating substrate having a lower electrode formed on a back surface thereof, as illustrated in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2003-508928 for example. A first spacer layer is formed on the first multilayer distributed Bragg reflector (DBR) layer. An active layer equipped with a quantum well is formed on the first spacer layer. A second spacer layer is formed on the active layer. A second DBR layer is formed on the second spacer layer. An upper electrode is formed on the second DBR layer. Then, laser light having sharp directivity in a direction orthogonal to the substrate (direction parallel to stacking direction) is generated by applying a driving signal between the upper electrode and the lower electrode.
In such a vertical cavity surface emitting laser, the current density supplied to the active layer is increased while the current consumed is decreased and therefore in the vertical cavity surface emitting laser of Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2003-508928 a region is formed in the second DBR layer in which a current aperture is narrowed by an oxidized layer.